Plant disease resistance is an important trait in plant breeding, particularly for production of food crops. Downy mildew, caused by the plant fungal pathogen Peronospora farinosa f. sp. spinaciae, is an economically important disease of spinach worldwide, particularly for Spinacia oleracea, the most commonly cultivated spinach variety. Currently, fourteen races of the Downy Mildew (DM) causing pathogen are officially recognized, although new isolates are currently being discovered and named each year. To date, it has been believed that resistance to DM in spinach was race-specific. The ability of new strains of the pathogen to overcome resistance in spinach plants thus makes the development of spinach varieties with effective levels of resistance to Peronospora farinosa f. sp. spinaciae challenging and increasingly important.